I like to pack a roll of quarters in my carry-on and keep it in my rental car's center console throughout my trip, to cover any tolls I might encounter. Having quarters is convenient when there are automated exact-change lanes at the toll plaza. Usually I only need them for the tolls to and from MCO, but once in a while I take a toll road to get somewhere else.
I prefer to take the South Exit from MCO, and take SR417 (the Central Florida Greenway) to WDW. Tolls on SR417 each way are $2.50 (2x$1.25). I find 417 to have less traffic than the Beachline, and it gets me to WDW faster. Take Exit 6, which puts you onto World Center Drive and sends you directly into the heart of WDW property in the Epcot area. Once inside WDW, World Center Drive changes names and becomes Epcot Center Drive. It crosses Buena Vista Drive, giving you easy access to the Epcot, AK, and DTD area resorts, and it dead-ends at World Drive, giving you access to the MK area resorts.
If you need to make a grocery stop on your way from WDW, there are several options:
1) Get off at Exit 11; there is a Super Target on the south side of the highway (turn right at the end of the exit ramp).
2) When you get off of 417 at Exit 6, hang a left at the first big intersection, SR535. There is a Walmart supercenter about 2 miles down on the right, and a Publix about a mile further on the left.
3) When you get off of 417 at Exit 6, hang a right at SR535 and this will take you to the Crossroads shopping center, where you can pay way too much at Goodings.